Deposition of Molybdenum-Carbide thin films by Dense Plasma Focus Device

Kishawar Khan

Abstract

Deposition of Molybdenum-Carbide thin films by Dense Plasma Focus Device

This work is motivated by the promising physical, chemical
properties of molybdenum carbide such as high melting
point, high resistance to corrosion and oxidation, and
good electrical conductivity, and its catalytic activity in
several applications such as the production of sustainable
energy and fuels, the decomposition of hydrazine in the
micro thrusters of satellites, water-gas shift reaction, etc.
However, the films have some defects such micro-cracks,
micro-craters, rough surfaces and impurities like silicon
and silicon carbide, but it’s the first ever successful attempt
to deposit molybdenum-carbide (Mo2C) thin films
using dense plasma focus (DPF) device. The samples
were processed by multiple number (5, 10, 15 and 20)
of focus shots, and characterized by several techniques
such XRD, SEM, Ellipsometry and Four-Point Probe.
The XRD results showed the dependence of crystallinity
on number of shots. The crystallinity was increased
by increasing number of focus shots. The SEM images
showed non-uniform films with some surface defects
such as micro-cracks, micro-craters and rough surface.
The ellipsometry technique showed the increase in the
film thickness by increasing the number of focus shots.
The electrical conductivity of the films measured by fourpoint
probe technique, first increased for 5 shots and 10
shots and started to decrease by further increasing the
number of focus shots to 15 and 20. The maximum electrical
conductivity of the film ( ~4.14 ×Ã£??10Ã£??^(-2)/Ω-cm)
was observed for 10 focus shots, which is unfortunately,
very much less than the actual electrical conductivity of
molybdenum carbide ( ~1.75 ×Ã£??10Ã£??^4/Ω-cm), which was
attributed to the presence of silicon (insulator at room
temperature) in the films.